Technical Field
The invention relates to an apparatus for compacting fibrous plant material, in particular for compacting stalk material, having a feeding device for feeding the plant material or stalk material to be compacted and having at least one pair of press drums that are settable into opposite rotational movements.
Prior Art
The utilization of renewable raw materials, such as fibrous plant material, is increasingly gaining in importance. Thus, renewable raw materials, such as wood, but also harvested stalk material, for example straw, can be utilized further, for example for the purposes of bedding or combustion. In this case, it has proven very advantageous to pelletize such raw materials and to compact them to form pellets.
U.S. Pat. No. 3,613,335 discloses an apparatus, to be towed by a towing vehicle, for pelletizing materials, having two press drums that are drivable in opposite directions. In order to gather the material to be pelletized from the ground, provision is made of a pick-up apparatus which conveys the material to be pelletized in the direction of a feeding device. The feeding conveying device consists of a conically configured drum that is drivable about an axis that is inclined with respect to the press drums, and also of a further drum which is arranged coaxially with a first press drum and is firmly connected thereto. This further drum runs in an internal recess of the conical drum that is arranged in an inclined manner. The material to be pelletized is thus moved via the coaxially arranged drum and an end-side face of the conical drum transversely to the direction of travel of the apparatus in the direction of a filling region between the press drums, and in the process is compacted to a small extent. A disadvantage with this apparatus is that, on account of lacking or insufficient counter-pressure, no effective compaction can take place. On account of the lateral feed of the material to be pressed, only very narrow press drums can be used for producing pellets. Thus, only a small throughput is achievable.
DE 20 2009 001 697 U1 discloses an apparatus for pressing pellets, which has a pair of press drums arranged downstream of a feeding device, said press drums rotating in opposite directions. One press drum has press channels that are open toward an internal cavity and which each have a receiving groove space in their upper region facing the circumference of the press drum. The press drum having the press channels is assigned the other press drum which has compression rings with cylindrical press punches. During rotation of the press drums, each particular press punch passes into the associated press channel, on passing through or passing the connecting plane in which the rotation axes of the press drums are located, in order to plug the material to be pelletized into the press channel and form it into pellets. In this apparatus, free-flowing material to be pressed is fed to the press drums by a feed conveyor in the form of a screw. Such a feeding device is not advantageous for stalk and plant material.